Writing instrument



FIG. 1 is a perspective view of a writing instrument showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a right view thereof;

FIG. 5 is a left view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof; and,

FIG. 8 is a front view of the writing instrument in an extended state.

The broken lines show portions of the article that form no part of the claimed design. 

CLAIM The ornamental design for a writing instrument, as shown and described. 